Pigeons, and droppings cause by the pigeons, is a constant menace to bridge inspectors and bridge maintenance crews. Some bridge steel members or structures such as, for example, box beams have interior spaces that are enclosed except for access openings. The access openings are provided so that bolts can be tightened on the interior sides and/or bridge inspectors can look inside for signs of fatigue cracks etc.
These access openings can also be used by pigeons to get inside the steel members and build nests. With pigeons in the bridge come heavy amounts of droppings. The pigeon droppings can be corrosive to the metal and can obscure surfaces that need to be inspected. As a result, bridges need to be cleaned before they can be adequately inspected. The cleaning of a bridge alone can be very expensive.
Several methods have been used to keep pigeons from accessing interior portions of steel members. One method is to bolt metal covers over the access openings. However, it is time consuming to remove and reinstall the covers for each inspection. As a result, the cost can be nearly as much as cleaning the bridge. Another method is to clip plastic covers over the access openings. For example, see U.S. Pat. No. 5,209,032, the disclosure of which is expressly incorporated herein in its entirety by reference. However, these plastic covers are only slightly less time consuming and expensive to remove and reinstall for each inspection. In fact, some people have questioned whether not removing plastic covers limited the views of inspectors prior to the collapse of the I-35W Mississippi River bridge in Minneapolis, Minn. in 2007. Accordingly, there is a need for improved devices and methods for keeping pigeons out of the interior portions of steel members.